Corrosion of metal surfaces in aqueous media has long been a problem for industries such as oil and gas, food and beverage, washing and sanitizing, pulp and paper, power generation, manufacturing, and utilities. For example, it is well known that during the production of oil and gas several corrosive components such as brines, organic acids, carbon dioxide, hydrogen sulfide, and microorganisms are present in various capacities. These harsh conditions can cause severe corrosion as evidenced by surface pitting, embrittlement, and general loss of metal. The metal surfaces can be composed of a high alloy steel including a chrome steel, a ferritic alloy steel, an austenitic stainless steel, a precipitation-hardened stainless steel, a high nickel content steel, copper, and a carbon steel.
In general, corrosion inhibitors protect the metal through formation of a passivation layer on the metal surface. This passivation layer wets the metal surface, which in turn prevents contact of the metal from the corrosive nature of the fluids. Typically, corrosion inhibitor formulations contain a variety of aliphatic organic surfactant molecules including amines, quaternary amines, imidazolines, phosphate esters, amides, carboxylic acids, or combinations thereof. However, in harsh environments (e.g., high salt and acidic pH) the formation of a passivation layer on the metal surface is decreased and the susceptibility of the metal surface to corrosion is increased.
Mitigation of corrosion and fouling is advantageous in all water based or aqueous systems. In the prior art, most of the additives that are commonly used for corrosion and fouling mitigation include phosphorus, such as orthophosphates, polyphosphates, or organic phosphates commonly known as phosphonates. While there has been some success attributed to phosphorus containing corrosion and fouling inhibitor compositions, it has recently been discovered that phosphorus is not environmentally friendly. As a result, environmental agencies have either mandated a reduction in its use or banned its use altogether.
Thus, there is a need to develop methods and chemistries to inhibit corrosion of metal surfaces exposed to harsh environments. Additionally, there is a need to develop methods and chemistries to inhibit corrosion of metal surfaces without the need of phosphorous or zinc.